Help me analyze this please.

[LarryM]

Ok, I went and bought myself a chronograph, Chrony Beta Master. So far it has worked fine and been a bit of an eye opener.

But his is the load I'm working on.
.30-30 Marlin 336T 18" barrel, Weaver K2.5
Lyman 311041 of ACWW comes in at 175gr
Winchester cases
CCI 200 primers
32 gr W748
C.O.A.L. 2.525

I shot 2 5 shot groups over the chrono out to 50 yds, 1st was 3/4" with my called flinch flyer oepning it to 1.5", second group was 1.75" but I probably didn't let hings cool down enough. That and it was gusting to 25+mph pretty much right to left that afternoon but mostly I think it was me.

Anyway, this is what the chrono told me about my load
avg. vel - 1972
ES - 55.06
SD - 15.71

I'm seeing the slightest of cratering on the primer so I'm going to back this down a bit but does it look like I'm on the right track?

[high standard 40]

Others may have a different take on this but this is my opinion. Years ago I purchased an Oehler 33 chrono and started using it for load development. It was as you say an eye opener. A lot of useful data from that piece of equipment. After using it for a few years what I have settled on is it only tells part of the story. The target tells the most important story of all, group size. The chrono will not always tell you what your best load will be. Many times I have tested loads with a high standard deviation that would deliver much better groups than another load with a very low standard deviation. Has to do with barrel harmonics. I don't intend to downplay the value of a chrono. Knowing your average velocity is very useful. I just stopped paying attention to the other figures and just look at group size on the target. As a matter of fact, my chrono has not been out of the case in several years. I now use published data, work up slowly, and adjust till I can get good groups on the target. My range time is limited and that is a factor. When I retire, I hope to change that and take the old chrono back out and start using it again.

[fourarmed]

I agree! If the boolit doesn't suit the gun, It's going to spray them all over the landscape, and it doesn't matter if the SD is zero. On the other hand, very large ESes (bigger than 100 fps) can tell you that you are not getting consistent ignition, which is good to know. That may not show up on the target at only 50 yards. You can compare your velocity to pressure-tested data for the same powder and boolit, and have a much better measure of pressure than you can get from looking at the primer. But standard deviation is not something to obsess over. For one thing, it is hopelessly inaccurate when based on the 3, 5, or even 10 shot samples most of us settle for.

[454PB]

+2. I use my chronographs to develop loads with component changes or when using powders which have scarce published load data, but grouping ability is done seperately. For me, there's no sense wasting time and effort on a particular recipe that doesn't shoot accurately and group well.

I have looked at published load data differently ever since I bought my first chronograph 35 years ago.

[jsizemore]

LarryM, I think your on the right track. Your groups probably have to do with a skinny forend and 25+MPH gusts. Single digit SD and ES are nice if your shooting a target rifle at targets. If it happens with a plinking or hunting gun, your a lucky man and should play the lottery often. I would try a powder a little slower and a one a little faster. If they don't work out, you still have powder. You can never have too much powder. You might end up with single digit SD/ES. When I shoot a powder in a new gun I look to see that I'm in the operating range of that powder. Look down the bore after you shoot, and if you see a dull/sooty appearance to the barrel you ain't there yet. Good luck with your load development.

[Newtire]

Larry,
That is a great load if you ask me. I have loaded that and another of 30.5 grains H-335 with that boolit 311041. The H-335 is a little faster than the 748 in the stuff I have so I wouldn't go more than this Will have to give them a run thru the chrono & see. I have the Chrony Beta Master also. It seems to go for a long time and then starts giving me errors until I turn it off & restart it. It makes things more fun for sure and puts the "real" into velocity.

[AZ-Stew]

I'm with Newtire. Everything you mention is "average" for what you're doing. Nothing wrong with it, nothing spectacularly good about it. It's what I'd expect to see, considering what you're working with. As he says, it's a good load. Any deer within 150 yards is in peril.

I wouldn't consider it a benchrest load, but there's certainly nothng wrong with it and you chrono reflects what you see on paper. Don't obsess over it. Find a load that groups well, then chrono it so you know what you have. If you know the ballistic coeffficient of your boolit (I'd like to know where I can find a chart (??)), you can predict the trajectory using a ballistics program. Remember, though, this is not an absolute science unless you know the altitude, temperature, humidity and a few other things I've probably forgotten. Bottom line here is that you need to practice for long range shooting so you know where to expect the bullet to land at extended range.

If you're working on the upper end of loads, the chrono will suggest to you when you're approaching the limits. Someone smarter than me said that it takes a certain amount of pressure to launch a given bullet weight to a particular velocity. When your chrono tells you you're exceeding the velocity of factory loads, you should begin to suspect that your loads exceed factory pressures, assuming the same bullet. Very logical. I should have figured this out for myself.

Regards,

Stew

[LarryM]

Thanks guys.